A low angle laser light scattering photometer, capable of accurately determining the weight-average molecular weight as well as the diffusion coefficients of the systems of interest, will be the analytical tool of choice for measuring and correlating size, shape and the dynamic properties of biologically important macromolecules, phospholipid vesicles and cell membranes. The diffusion coefficient will be used to rapidly size potential drug encapsulating phospholipid vesicles. Changes in size and shape caused by aggregation and/or fusion of these lipid vesicles and/or cell membranes as experimental conditions vary will be followed by light scattering. The molecular weights of lung surfactant proteins and DNA segments will be determined. The rotational and translational diffusion coefficients obtained by this dynamic light scattering technique will be used as an independent verification of NMR data obtained on hydrated biologically important macromolecules. Finally, these light scattering techniques will be used to monitor DNA-Drug interactions.